Absorbent articles such as baby diapers, feminine hygiene products, adult incontinence products or wipes are known in the art and substrates made of synthetic polymer material, synthetic fibers and/or natural fibers are commonly used in such absorbent articles, for example, as topsheet material, as core wrap to enclose the absorbent material in the absorbent core, but also in acquisition systems of absorbent cores.
Often, such substrates are per se hydrophobic. However, for many applications in absorbent articles it is necessary to have substrates of a suitable hydrophilicity.
A topsheet, for example, is typically a substrate designed to provide an interface between the wearer and the absorbent core of an absorbent articles as well as to provide the first point of contact for any bodily waste exuded by the wearer. Topsheets may be made form a film, such as an apertured film, or they may be made of nonwoven webs. These films or the nonwoven webs often need to be rendered hydrophilic.
A common method for rendering substrates hydrophilic is coating the surface of the substrate with hydrophilic surfactants. However, surfactants may be washed off during use when the absorbent article is wetted.
This may typically lead to a decrease in hydrophilicity of the substrate and for example in a decrease in the substrates permeability leading to a performance reduction during use on absorbent articles comprising such substrates.
While durable hydrophilic polymer coatings, when used instead of the surfactants, may be more resistant to washing off, they can also be brittle which can lead to breaking of the coating when the substrate is stretched or bended, for example due to process steps or typical movements of the wearer.
Thus, there is a continuing need for further improving the properties of hydrophilic coatings, such as for example improving their mechanic stability towards bending and/or stretching of the substrates.
The inventors have developed new substrates coated with a specific block copolymer as described herein. The resulting coated substrates have been found to show a good hydrophilicity as well as a good stability of the coating upon bending and/or stretching of the substrates.